1. Field of Invention
The present invention relates to a method and a system of determining failure of a urea level sensor. More particularly, the present invention relates to a method and a system of determining failure of a urea level sensor which can determine failure of the urea level sensor indicating lack of urea in a urea tank to a driver.
2. Description of Related Art
Generally, urea level sensors are divided into continuous type urea level sensors and non-continuous type urea level sensors. The continuous type urea level sensor is a sensor which continuously detects a urea level using ultrasonic wave, and the non-continuous type urea level sensor is a sensor at which electric contacts of a switch are contacted with each other if the urea level reaches a predetermined level, and thereby indicating a current urea level is the predetermined level.
Each of the continuous type urea level sensor and the non-continuous type urea level sensor has merits and drawbacks. Particularly, the continuous type urea level sensor, compared with the non-continuous type urea level sensor, has merits of assisting a modeling of a urea consumption during a vehicle travels, facilitating release of a compulsory inducement state for a driver (i.e., a state where the driver is forcibly induced to put in the urea because of lack of the urea) when the urea is replenished during the compulsory inducement state for the driver, and allowing the driver to predict replenish timing of the urea since the urea level is shown on a cluster.
In a case of using the continuous type urea level sensor, however, stuck or drift of the urea level sensor can be diagnosed. Recently, regulations demand that the driver is warned and is forcibly induced to replenish the urea if there is lack of the urea in a urea tank. A method of determining failure of the urea level sensor is essentially applied so as to meet the regulations.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.